This contest would only go four simulated innings, but the results were encouraging for Cooper, Robinson and pitcher Wandy Rodriguez, the subject of the exercise.
Rodriguez threw 80 pitches without incident and will now head to the Minor Leagues for a rehab start or two before hopefully rejoining the Astros in a week to 10 days.
"I feel fine, no [discomfort]," Rodriguez said after pitching to J.R. Towles, Jose Cruz Jr., Geoff Blum and Michael Bourn during a simulated game that lasted approximately one hour. "[I'll] go to [Double-A Corpus Christi] and throw maybe a normal game."
Rodriguez, who has been on the disabled list since April 20 because of a strained groin, is the lone left-hander in the rotation. He is 1-0 with a 2.31 ERA in four starts.
"[Rodriguez] threw fine, stepped it up a little bit," Cooper said. "He looked pretty good today. [There] weren't many balls hit hard, so that's a good sign."
Robinson was also encouraged by Rodriguez's performance.
"We want to make sure that [groin is] healthy," Robinson said. "His arm has been strong, his pitching solid; we just want to make sure his legs are OK for him to throw, and from what we saw today so far, he's completely healthy. His stuff was good. We had him throw 80 pitches, so we're really encouraged with what we saw today."
Towles agreed Rodriguez looked good.
"It didn't look like his leg was bothering him," Towles said. "He had a good fastball and command of all his pitches."
Cooper said Rodriguez will probably throw a light bullpen session on Monday in Houston and then make his rehab start on Thursday. It is uncertain whether Rodriguez will need one or two rehab starts. If it's only one, he could return for the series at St. Louis May 27-29.
"We'll play it by ear," Cooper said. "[It] could be two [starts], but no more than that. We're just trying to plan it to slot him in whenever he's feeling his best."
Jim Molony is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.